Safety fuel ignition device



Nov. 10, 1942. v. D. OTT

SAFETY FUEL IGNITION DEVICES Filed May 27, 1940 3 Sheets-Sheet 1 a g g 6 fzodejaim'. flo ze a 052 Nov. 10, .1942.

v. D. on-

'SAFETY FUEL IGNITION DEVICES 3 Sheets-Sheet I5 i yoyze p. 0 670 6'1- Filed May 27, 1940 Patented Nov. 10, 1942 UNITED. v STATES PATENTlOFFICE sars'rr roar. IGNITION nsvrcn Yoyle D. Ott, Racine, Wis, assignor to Webster Electric Company, Racine, Wis, a corporation of Delaware Application May 27, 1940, s mi; No. 337,369 10 0mm. (Cl. 158-28) The present invention relates to safety fuel ignition devices, and is particularly concerned with control transformers and circuits for the control of the fuel supply and ignition of the various types of fuel combustion systems. It is applicable to all types of fuel combustion systems,

such as oil burning or gas burning, or otherwise,

in which the fuel is adapted to be ignited by means of an electrical spark.

One of the objects of the invention is the pro vision of such a safety fuel ignition transformer that it will only operate the fuel control when the spark is of proper value, and will not operate the auxiliary apparatus on open 'circuitor short circuit.

Another object of theinvention'is the provision of an improved safety fuel ignition system in which the blower for combustion air is adapted to be started before fuel is supplied so that an ignition spark may be established across a gap and the spark may be lengthened due to the action of the air blowing on it at any of a plurality of different high rates of air feed, by means of which fuel will not be supplied to the burner if there is a short circuit in the secondary circuit or an open circuit inthe secondary circuit of the ignition transformer or if satisfactory spark. conditions' are not established'with the blower operating at high speed and extending the arc.

One of the objects of the present invention is v motorand blower, and it also has auxiliary contacts for controlling another magnetic switch.

.These auxiliary contacts, according to one embodiment of the invention, are connected in series with the energizing coil and auxiliary coil located on the same leg of the ignition transformer.

The same magnetic switch is adapted to operate a. fuel control means, but only in the presence of anelongated 'sparkflowing across the spark gap which is produced by the blast of air from the blower under proper ignition conditions.

In the absence of such a spark, or if there is a short circuit, no fuel whatever will be delivered to the combustion chamber of any fuel system embodying my invention.

I desire it tobe understood that the present transformer may be used with other combustion control systems than those which are exemplifled in the accompanying drawings and description, which are merely exemplary of several forms of control systems that may be used.

Referring tothe three sheets of drawings accompanying the specification, I Fig. 1 is a wiring diagram including diagrammatic representations of the circuits and various elements of a safety fuel combustion system embodying my invention; .Fig. 2 is asimilar wiring diagram and diagrammatic representation of the elements of a modified form of system;

Fig. 3 is a fragmentary elevational view, of one form of thermostatic stack switch which may be is adapted to positively prevent the delivery of fuel to the combustion chamber whenever there is no spark across the electrodes.

Another .object of the invention is the pro-- vision of an improved safety fuel ignition system of the class described which is adapted to be embodied in a-continuous ignition system or an intermittent ignition system. 1

The present safety fuel ignition system includes a transformer which is adapted to supply the ignition current at suitable voltage and which is also adapted to operate a pair of magnetic switches. a

One of these switches is adapted to control a employed in thesystem;

Fig. 4 is a sectional view, taken on the plane of the line 4-4 of Fig. 3, looking in the direction of the arrows, showing the arrangement of the movable switch arms and contacts of the switch of Fig. 3;

Fig. 5 is a' wiring diagram of another modiflcation of the system showing the adaptation of my safety ignition transformer and system to an intermittent ignition system.

Referring to Fig. 1, It indicates in its entirety a safety ignition transformer embodying the fea-' 'tures of the present invention.

It preferably consists of a closed circuit core ll of magnetic metal of the shell type, having a central leg I! joined to the two side legs I! and II by the end portions I! to II, the cross sectional area of the portions I! to II, and the outer leg; II and I4 being substantially half 'of the cross sectional -area of the middle le ii.

The middle leg I! preferably supports the primary coil 2| at one end, and at the-opposite end it carries the secondary coil fl and the auxiliary the secondary will be maintained substantially coil 22. The terminals of the secondary coils are connected by the conductors 22 and 24 to the electrodes 25 and 28, respectively, which are spaced from each other to provide th spark gap, which is indicated by the numeral 21.

The primary coil 20 includes a suitable number of turns of wire of relatively larger size than the wire used in the secondary coils 2|, which are smaller, and which include a greater number of turns, depending on the voltageratio, or increase in the voltage desired between the primary and secondary.

The transformer is provided with a pair of magnetic shunts 28, 29, which are located between the central leg l2 of the core and each of the outer legs l3 and I4, and which separates the primary coil from the other two coils.

The shunts 28 and 22 afford a magnetic leakage path of high reluctance, and are adapted to control the current in both the secondary and auxiliary windings 2| and 22, respectively. These shunts are so designed that a higher voltage is generated in the auxiliary coil 22 when the secondary is operating on extended spark, by virtue of the air passing over the spark gap.

The reluctance of the shunts 28, 2! is such that they maintain a constant voltage in the auxiliary coil 22, with a fluctuating line voltage under the operating conditions of a sparkgap.

The air which is passing over the stationary or fixed gap ,produces an elongated spark and generates a lesser countermagnetic motive force in the leg l2. Due to the reduced flux density in the leg i2, less iiux will be by-passed through the magnetic shunts 28 and 22, due to their high reluctance.

This permits more flux to cut the auxiliary coil 22, and generates a higher voltage in the auxiliary coil 22 than when the transformer secondary 2i is short-circuited, or whenit is operating on a fixed gap in still air.

The reactance of the transformer increases with leakage of magnetic flux. Therefore, when a lower primary voltage is applied to the primary of a high reactance transformer, there will be a lower flux density generated in the core leg l2. and there will be less magnetic flux by-passed by the magnetic shunts 22, 2!. The transformer will, therefore, generate a fairly constant voltage.

On the other hand, should a higher voltage than normal be applied to the primary 22 of the transformer ill. a higher flux density will be generated in the core leg l2 and a greater counterelectromotive force generated by the coils 2| and 22, during the operation.

Then a greater amount of flux will be bypassed by the shunts 2|, 2!, and the voltage at constant. 6O In other words,the reluctance of the shunts 22, 22 is such that they maintain a substantially constant voltage in the auxiliarycoil 22, with a flue--v tuating line voltage under the operating conditions of a spark gap.

A lower voltage in the primary will produce a' lower flux density in the core II, and therefore less flux-will be by-passed by the shunts 20 and 2| due to their high reluctance.

A higher voltage in the primary will produce a high flux density in the core ii, and therefore a greater flux will be by-passedby the shunts 22,

2|. Thereforefthese shunts produce a relatively steady current inthe auxiliary coil 22, which permits the relay It to function satisfactoril over a 76 considerable range of operation in primary voltage.

These shunts and the core I I include a plurality of laminations of magnetic metal, such as 5 soft iron, suitably secured together, and the shunts 28 and 28 are spaced from all of the legs 12 to l4 by air gaps, indicated at 20, ii, 32,

and 33.

One of the terminals of the primary coil 20 is connected at W to a conductor 38 which leads to the source of supply of alternating current to other suitable controlling devices, further to be described.

fixed contacts, 4| and 42, and a pair of movable contacts 43 and 44, the movable contacts being controlled by the energization of the relay coil 28. The other terminal of the relay coil 3! is connected by conductor 45 to a conductor 4!,

which leads to one of the alternating'current line conductors 41.

The line conductors 41 and 48 may consist of any standard IIO volt lighting circuit alternating current supply. The auxiliary coil 22 preferably has its windings located under the secondary coil 2! to get the best results or located at,,the end of the leg 12 opposite from the magnetic shunts 28 and 29.

One of the terminals of the auxiliary coil 22 is connected by conductor III to the controlling coil ll of a magnetic relay having a fixed contact l2 and a movable contact 52. Theother terminal of the relay coil BI is connected by conductor 54 to the movable contact 44 of the relay 40.

It will thus be observed that the relay 2! controls the energization of the relay coil ll, The relay, including this coil and contacts I2, 52, may be indicated in its entirety by the numeral N.

The other terminal of the auxiliary coil 22 of the transformer III is connected by conductor ll to the fixed contact 42 of therelay". The fixed contact 4! of the relay 40 is connected by conductor 62 to the conductor 48, previously mentioned as being connected to the line 41.

Movable contact 42 of the relay 40 is connected by conductor 82 to the energizing circuit 0 of the motor III of a motor driven blower, which has a terminal box '4. The other lead from the terminal box 64 of the motor 10 is connected to conductor ll. 88 indicates a motor driven fuel feeding means, such as a liquid fuel pump, or it may consist of a magnetically controlled valve for controlling the supply of gaseous fuel to a nozzle fll.

For example, the pump may be driven by a separate motor, energized through conductors 1,

I2, or the pump may be driven by the blower motor and controlled by a solenoid at 8.

Conductor '8, leading from the fuel control means 85, is connectedto the movable contact II V of the relay OI.

Referring now to the upper part of the diagram of Fig. 1, II indicates the limit control switch. which is interposed in the line conductor l8, l2 leadingto the primary 1! of a transformer. Thus the limit control switch is adapted to disconnect the entire energizing system when it is actuated. 1

The transformer, indicated at 14, also includes the core II and secondary ii for energizing the various controlling devices at the upper part of the circuit. A conductor I1 leads from the conductor 12 to the fixed contact 10 of an alternating current relay, which has a plurality of fixed contacts 10 to The coil of this A. C. relay is indicated by 02, and the movable contact arms by 03 to 00. Conductor 30 is connected to the movable contact arm 80,'so that the energization of the motor driven blower is controlled by the relay 02.

The movable contact arms 00 to 00 are connected together by a conductor 01 for the purpose of controlling the common connection oi the contacts 10, 00 and BI together. 00 indicates .a stack switch which is adapted to be controlled and actuated by a helically coiled by-metallic element SI, which is locatedin-the stack leading from the combustion chamber.

One end of the coiled bi-metallic element 0i, such as, forexample, the end 02, may be fixed.

\' One end, such as the end 02, is fixedly secured to a suitable support. This thermostatic switch 00 is further illustrated in Fig. 3, and arranged as follows:

The other end 03 of the thermostatic elementv is secured to a pin 90, carried by a disc 90, which is rotatably mounted on a trunnion 00 carried bythe shaft 91. The support for the fixed end of the bi-metallic element 0| may consist b1 a bracket 98 fixedly secured by an angle 99 to the wall I00 of the stack.

The rotatable disc 95, which is actuated by the bi-metallic element Si, is frictionally engaged I00, I09. These contacts are also similarly indicated in the diagram Fig. 1. The two contacts I00, I00 are connected together with a conductor 0, which also extends to one of the terminals of the relay coil .02. The other terminal of the relay coil 02 is connected by conductor III to a fixed contact II2 of a bi-metallic stack switch,

the bi-metallic element being indicated at I I2.

There is an electrical resister IIO in close proximity to this bi-metallic element H0; for example, the resister maybe wrapped about the bimetallic element with suitable insulation interposed. The resister IIO has one of its terminals connected to the conductor IIO, and the other connected to a conductor IIO, which leads to the fixed contact I01.

The fixed contact I00'oi the thermostatic stack switch" is connected by conductor II1 to the fixed contact II or the relay, which is indicated in'itsentirety by the numeral I20. The fixed contact 00 of this relay is connected by conductor I2I to conductor I I0, and conductor I I0 is extended to a fixed contact I22 of the room thermostat I00.

The room thermostat may comprise any suitable iorm of thermostatic switch, such as a bimetallic thermostatleeiement I and an'elongated switch arm I20.

The switch arm I20 and thermostat I22 serve as conductors, being connected to the'conductor I20, which is connected to fixed contact 10 oi the relay I20. The fixed contact I20 of the room 3 to one terminal of the secondary" of trans former 10.

The room thermostat a'rm I20 also preferably carries a resilient movable contact member I20,

which emgages'its fixed contact I22 only after there is firm engagement between the end of the utilized with other controlling circuits than those which are exemplified at the top of Fig. 1 and connected to the lower relay circuits and transformer by the conductors and 00. The complete system is illustrated in this preferred form for the purpose of'illustrating the safety, operation of the fuel supply system. v

The operation of the system is as follows: The control transformer 10 is at all times connected to the line on the primary side through the limit control switches. As the room temperature de-- clines, the room thermostat I00 first makes contact with the fixed contact I 20, but the circuit of the secondary coil 10 is still open on the main control relay at 10, 00, and thus no operations of the burner are instituted.

A further decrease in the room temperature The thermostat H3 and heater H0, and fixed contact II2 make up a warp switch, which is indicated in its entirety by the numeral I30; The energization of the relay winding 02 closes all of the tour contacts 10 to 0| and 00 to 06 or this main relay switch.

' ;The right hand contacts 10 and 86 are in connection with the motor 10 01' the motorblower '01. These two contacts 10 and 00 are also connected to the primary of the ignition transformer through conductors 00, 00, 01, relay coil 30, co nductor 00, conductor 00, and 01. Thus the right hand switch'oi' the main relay, by-contacts 10 and 00, is adapted to'start both-the motor and the ignition transformer.

The next two switches to the left in the main relay- I20 are adapted to complete' the transformer circuit for eliminating the control by means of the contacts I22, I20 01 the room thermostat from the circuit, .but maintaining the how,

of secondary current through the heater coil I I0,

' through the solenoid winding 02. and the warp switch I00 backto the secondary.

It will thus be observed that the movable contacts 00 and 0.0 will connect the fixed contacts 10 and 00 together sothat both of the circuits III and I20 from the thermostat I20 and the contact I22 are connected to'the conductor H0.

1! no ignition or flame occurs at the burner, the continued ilow of secondary current through the heater I I0 will cause the warp switch or thermostat II! to become warped, and it will'open into a locked position, indicated by the latch I00.

' whichholds' the'thermostatJIl out of contact thermostat I30 is connected by one conductor I21 7 and this renders the burner inoperative by opening the contacts of the main relay |2|l until it is reset manually by means of a button or other manual device, actuating the latch I26, to release as the cold contact, and the contact Hi6 as the hot contact. The temperature rise by heating of the thermostat Si in the stack Hi causes the discs 95 and NI to move together in such manner that the pins I04, "I move toward the right in Fig. 1 on a rise of temperature. The arm I08,

engaging. the hot contact llll, is actuated by a spring I21, and the spacing of the pins I04, I0!

is such that contact is made between the arm I 08 and contact Ill! before it is broken at contacts I01, I" by thepin I05.

After the contacts I, I0! are in engagement and the contacts I21, I" are broken on an in* crease of temperature, a further movement of the thermostat Si is permitted by the frictional engagement between the discs and "II, which slip on each other, permitting the disc |0| to stand still.

However, immediately upon any cooling of the stack and the stack thermostat 8|, the two discs 2! and lfll (Fig. 3) move together again, due to their frictional engagement. This causes the pins Hi4, ill! to move toward the left immediately. This brings about an opening of the hot contacts I", I first, and thereafter the engagement of the insulating block I28 with the rarrnlolgl causes a closing. of the cold contacts The circuit is then in condition to be re-started upon room demand for heat, as indicated by the room thermostat Ill.

Referring to the lower part of the wiring diaam of Fig. 1, that is, that portion which is connected to the upper part by the conductors 2C and 40, the operation of this portion of the circuit is as follows. I

It has already been shown that the entire system is under the control of the limit switches 1|,

which control all energization, and the system is such that there is an adjustable period of opera-' tion during which the system will be energized for the purpose of igniting the fuel.

ondary coil 2|, a counter electromotive force will be built up in the central leg i2 of the transformer l0, thereby permitting a greater current to flow through the primary 20 of the transformer Ill.

This increased current in the primary 2|! of the transformer ill energizes the relay coil 2| and causes the contacts 44, 42 and 4|, 43 to close. It is the contacts 4|, 4! that control the blower circuit and operate the blower when current is flowing in the secondary 2|, as Just described.

In the event that current in the secondary is actually flowing across the gap 21, the arc will be elongated by the air passing over the gap 21, permitting suificient current to be generated by the auxiliary coil 22 to energize the energizing coil 5| of the relay 80, which is connected in series with the auxiliary coil 22. v

The relay 60 then closes the contacts 52, 22, which "are in series with the fuel actuating or controlling means 65 in the form of a motor driven liquid fuel pump or a solenoid actuated valve for gaseous fuel.

The foregoing is the operation of the safety transformer when there is a proper ignition spark across the gap 21 adapted to ignite the fuel when supplied to the combustion chamber through the nozzle 68.

It should be noted that the electrodes 2!, 22 are preferably located Just outside of the field of spray of the nozzle, and the spark or are is blown into the range of the spray by the action of the air blast.

Thus the electrodes are not subject to accumulationsof carbon which would otherwise burn on'the electrodes and build up between them if This period will run its course, whether or not flame takes place. At the expiration of this period, if the flame does not take place, the entire fuel combustion, system is shut down, and can only be placed in conditionfor another operation by means of the manual control of the resetting latch I.

The purpose of the present safety ignition transformer'and system is to positively prevent the supply of any fuel to the combustion chamt ber unless the spark is in condition to effect ignition and flame. During the period of the energization of the transformer 0, the motor blower also has its motor energized, and 'a blast of air is blowing across the electrodes 2|, 2|, effectively lengthening the gap 21.

In the event of the flow of current in the secthe electrodes were located in the oil spray. In the event there is a short circuit in the secondary coil 2| oracross the gap 21 of the ignition electrodes and 28, a larger counter-electromotive force will be built up in the middle leg i2 of the transformer. This larger counterelectromotive force will permit the major portion of the flux that is caused by the energization of the-primary to be by-passed around the primary through the magnetic shunts 22 and 22. This reduced flux will not produce sufficient voltage in the auxiliary coil 22 to move the switch arm 24, 28, 21, 25, 22, there will not be sufllcient current flowing through the primary 2! to energize the coil 22 to move the switch arms 42 and 44 into engagement with the fixed contacts 4| and 42, respectively. v

of course, the energization of the fuel feeding means I is controlled through relay 5| by con: tacts 42, 44 of relay 22, and there will be no actuation of the fuel feeding means if the relay 2! is not sufficiently energized to move the switch arms 42, 44. Furthermore, the blower motor is controlled by the contacts 4|, 43.

Under these conditions, with no current flowing in the secondary circuit, the blower motor will not be energized either.

In the event of a short circuit in the high tension circuit, which includes the secondary 2|, conductors 22, 24, electrodes 2!, 2B, and El -D 21, which would cause the coil 22 to be energized,

between the laminations.

and-would permit the blower circuit to be energize. at ll, 48 and to operate continuously, the

fuel combustion system would be shut down by the control'circuits at the top of the diagram of Fig. 1, after the predetermined period of energization had run its. course. It should be noted under these conditions that the fuel feeding means 65 would not have been energized, at all.

In the eventof no current flowing in the high tension circuit, including the electrodes 25, 26

and gap 21, the relays l and 80 would not be energized,'and after the passage of the predetergrade C. The size of the core may be as fol-' lows: The width of the central le'g may be 1 The width of each of the side legs I! and I4 may be %2". The corners of the core may be rounded on so that they are described on a 952" radius.

The overall width of the core from the outside of leg II to the outside of leg I may be 4%".

The primary coil may consist of 314 turns of No. 18 wire, insulated with paper and enamel with a 10% lap. The size of the inside of the primary coil at the core may be l "x1% and the length of the coil may be The secondary coil 2i may consist of 15,000 turns of No. 39 wire, insulated with plain enamel, and with two wraps of .00075 Glassinepaper between each layer. The size of the secondary coil at the aperture for the core may be 19;" x 1%", and its length may be 11%". Two such secondary coils may be used to make up the secondary winding.

The auxiliary coil 22 may comprise 68 turns of No.22 insulated wire, the size of the coil apergufire being 1 "x 1 and the length being The relay coil No. 38 of the relay 40 may con- ,sist of 193 turnsof No. 19 paper enameled wire having paper lap, mounted on a round core, having a diameter of .510," and a length of The relay coil I of relay 0| may consist of 500 turns of No. 24 insulated wire. The core size may be round and%" long. r

The cores of the relays and the armatures may consisting of Armco iron, 1*", 1 wide x .093"

thick. The pole piece may be diameter by One of the problems involved is to have enough I current left in the ignition circuit above the retion transformer are started first; but there is no oil flow. When the blower is operating, the air blast draws out the spark. Then the present transformer and safety circuit have the capabil ity of differentiating between'a short and open circuit, the air gap at the electrodes under those conditions acting lik a wider gap. In the event the motor sticks or stops and the air blast ceases, the relay 80 cuts the circuit out.

Referring to Fig. 2, this is a modification of the invention utilizing a modified form of safety fuel, ignition transformer, which is indicated in its entirety in this case by the numeral I. This transformerihas its core H andmagnetic shunts 2| and 2! identical in construction to connected by conductors I", 8 to the 'terminals of the relay coil 38.

The operation of this embodiment is substantially the same as that of Fig. 1, with the following exception. A current flowing in the secondary 2| will cause counter-magnetomotive force to be built upin the leg l2, causing a portion of the flux to flow through the shunts "and 2!, ener- 38 is controlled by the coils in, I located on .9667" long. The shunts may be 26 gauge thick,

1 long, and .944" wide.

These magnetic shunts 28, 29 may have 11% wraps of .005" Gummed Fish paper ,around'the outside of the shunt, to hold the shunt securely Forty-nine laminations may be used, having a weight of 5.32 ounces and a thickness of .015".

I desire. it to be understood that the foregoing specifications for the transformer andrelay are merely exemplary, and are not to be considered limitative in any respect. The operation of the present transformer and relays involves quantitative relationships between the current established at various conditions of operation, and therefore the foregoing specifications are merely given in order to provide complete information for the making of one preferred, embodiment of the invention. 1

gizing the coils m, us. By virtue of these coils being directly connected to the coil 38' of the relay '40, this will cause the contact arms- 42 and 44 to move into engagement with the contacts ll and 42. With the exception that the relay coil the shunts 28 and 20, this embodiment of the invention operates substantially the same as that of Fig. l, and will produce the same results. Referring now to Fig. 5, this is a schematic diagram and circuit for a safety fuel system embodying my invention, and arranged for intermittent ignition. I

Many of the elementsof this circuit are subences in the connection of some of the elements of the circuit, and additional elements included, in order that the ignition may be cut off after a predetermined period of operation, while theburner continues to operate if the room thermostat is not satisfied.

In this embodiment of the invention the warp switch I has its movable blade connected to the coil 82 of mainrelayglll by a conductor Ill. Thecontact H2 of the warp switch is connected by conductor III to the coil I! of relay 14. This is merely a reversal of the previous arrangement. The stackswitch II has its thermostatic element ll arranged to actuate a mercury switch ll2,- Q

which is provided with the contacts I", il I". Contact ilt'is connectedlby a conductor I" to the contact 4i of relay 48. Another conductor I51 extends from "conductor 58 to the coil 38 of relay 48.

The mercury switch I52 also has a centrally located contact I58, which is connected by a conductor I88 to the movable contact switch arm 88 of the main relay I28. The contact I54 of mercury switch I52 is connected by means of conductor I88 to the conductor .88, which leads back to the contact 53 of the relay 68. Contact I55 of the mercury switch I82 is connected by conductor I8I to the conductor 36, leading to the blower motor 18.

The primary 28 of the ignition transformer has one of its terminals connected by a conductor I82 directly to the line 48. The electric motor of the fan 18 has one of its terminals connected by the conductor I83 to the conductor 81 from the electric oil valve 85 and to the electric supply line at 48.

The supply oit' mercury I64 in the envelope of mercury switch 452 is sufficient to cover contacts I58 and I58, simultaneously, and it also soranged that contacts I58 and I58 connoc at with center contact I58 before the, circuit is broken between contacts I58 and I53.

In this embodiment the contact I88 is connected by a conductor I85 to the contact 88 oi? the main relay I28. Conductor II from the heater coil I I4 is connected by conductor I88 to the contact 8i.

The operation of this embodiment of the invention is as follows: When the temperature of the room cools down, the thermostat I23 of the room thermostat I38 first causes contact between the arm I24 and the contact I28, and thereafter between contacts I22 and I28. This permits low voltage current from the secondary of the step down transformer 14 to flow through conductor I21, contacts I28, I24 to contacts I28, I22, conductor II8, heater coil II4, contact I81, arm I88, conductor II8, relay coil 82, conductor I58, warp switch II8, contact II2, conductor I5I, back to the other side of the secondary winding 18.

This energizes the main relay winding 82, and it attracts the armature attached to the switch arms 8388, closing all four contacts of the main relay I28.

As in the previous embodiment, the closure of contacts 18, I8, and 8i, 83 merely bypasses the contacts on the room thermostat so that the low voltage current flows directly from contact I28 through the blade I24 and the two contacts mentioned to the resistance heater H4.

The closure of the contacts 88, 84 does nothing at this time, since that circuit is open at con- I tacts I88, I88.

The closure of contacts 18, 85 provides a pat for power current .to flow from the line 41 through conductor 11, contacts 18, 88, conductor I88, to the center contact I58 of mercury switch I82. This center contact is in connection through mercury I64 with contact I53, conductor I58, I81, coil 38, conductor 31, primary 28 of the ignition transformer, conductor I82, to line 48. Thus the closure of the main relay I28 energizes the primary of the ignition transformer.

If the secondary of the ignition transformer is open, there will be insufficient current flowing through the primary winding and through the relay winding 38 to operate the relay 48. Under these conditions nothing further will hap pen except that the continued flow of low voltage current through the heater coil II4 will cause to open position, where it will be held by a latch I38, similar to that described in connection with Fig. 1, and manual resetting and restarting oi the circuit will be required. This manual resetting is an indication of the fact that something has gone wrong with the system.

If, however, the secondary of the ignition transformer is not open circuit, then there will be suiiicient current flowing in the primary and in the coil 38 of the relay 48 to actuate the armature and close the contacts 42, 44 and H, 43. The closure of the contacts 4|, 43 closes a circuit to the blower motor 18 from the-line, as follows: Line 48, conductor I63, motor I8, conductor 38, conductor 83, contacts 43, 4|, conductor I51, conductor I58, contact I53, mercury I84, contact I58, conductor I59, contacts B6, 18, conductor TI, to line at 41. Thus the closure of contacts M, 43 starts the blower motor 18.

The closure of the contacts tit, W closes a circult through the winding 5i ay and through the auxiliary Winding Ii 01' the ignition transformer it").

. It the secondary is short-circuited, then there will be insufficient current flowing in this circuit, which includes the relay 88, and. this relay wiil not operate, with the result that no oil will be fed to the burner. Under this condition the flow of current through the heater II4 will again heat the thermostatic warp switch H8 and open the circuit at contacts H2, H3.

If, however, there is a normal spark at the electrodes, then sufficient current will flow through the relay 88 to close the contacts 52 and 53 leading to the electric oil valve 65, and the oil valve will be opened. so that fuel will be fed to the burner. Since the spark is now in proper condition, the burner should be ignited.

Of course, if there is no oil supplied under these conditions, then no ignition could take place, even though there were a normal spark,

' and under these conditions the warp switch would the warp switch I2 to become heated and move 7 again open. I

If the ignition of the burner actually takes place, the combustion will raise the temperature in the stack, and the thermostat SI of the stack switch will become heated and actuate the stack switch.

Contacts I88, I88 will first be closed by passing the heater coil H4, and thereafter the contacts I81, I88 will be opened. Since proper ignition has taken place, and as evidenced by combustion and heating ,of the stack switch, the warp switch heater H4 is now out of circuit.

The stack switch 88 also causes the mercury switch I52 to tilt, and, as previously stated, this switch is so arranged that the mercury I84 connects with contacts I58, I54, I55 before a break is made between contacts I58 and I83.

When contacts I58, I 54 and I55 are connected, the circuit is adapted to be maintained closed through the motor 18, and the electric fuel valve 85 or electric fuel motor 85, as the case may be, before the circuit is broken at I53. Breaking of the circuit at I53 cuts off the ignition because this contact is in the primary circuit of the ignition transformer I8.

When the room temperature is satisfied, the room thermostat opens, and the main relay I28 drops out, opening all circuits. The stack switch 88 then cools of! first, and opens contacts I88, I88, and then at some lower temperature closes the contacts I81, I88.

The mercury switch is also tilted back from the dotted line position of Fig. 5 to the full line supply, said fuel supply relay being in circuit with.

position, and the burner is then next ignition cycle.

If the flame should fail during operation, the stack switch would cool off and re-establish con nection between the contacts I53 and I58, and open contacts I06, I08. At a lower temperature contacts I01, I09 would be closed, and this would place the burner in condition for a new cycle of ignition. As the room thermostat would not yet be satisfied, the burner would then attempt to start, and the controls would then again go through their test cycle, as before.

If the condition which caused the fiame failure still exists, the burner will lock out on safety, no matter whether the cause is due to transformer trouble or lack of oil.

Of course, since the flame failed in operation under these conditions, the failure would surely be due to lack of oil.

While the description of the sequence of events in starting the burner takes a substantial time, it is a fact that when the main relay I20 closes, the events described take place immediately thereafter, so that the oil valve will either be opened at once, or definitely will not open at all. From there on, the heater causes the warp switch to lock out of position.

It will thus be observed that my safety fuel system is adapted to be used with systems or circuits designed for continuous or intermittent igniticn. All of my systems are so arranged that no oil can be supplied to the burner unless the spark is in proper condition for ignition. The existence of a short circuit or an open circuit will positively prevent the supply of any oil to the burner, and if anything should go wrong with the circuits, the main relay will be de-energizecl and shut the whole system down.

Therefore, the present ignition and fuel supply system is safe under all conditions.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a safety fuel supply system for combustion devices, the combination of a source of alternating current with a step-down transformer, a room thermostat for controlling electric contacts ready for the responsive to the demand for heat, a main relay controlled by said room thermostat and having contacts for controlling the energization of an ignition transformer, a thermostatic stack switch having contacts controlling the energization of said main relay, a warp switch having a therrnpstatic switch arm and an elaitffdlileater, contact means and latching means whereby the warp switch will hold the main relay winding on open circuit upon failure of ignition, said stack switch superseding said warp switch upon heating of the stack, an ignition transformer having a primary, secondary, and auxiliary windings, said primary being controlled by said main relay, and having a magnetic core with a plurality of legs, said primary being located on said core, and said core also supporting said secondary, and said auxiliary winding, an electrically actuated source of air supply for the burner, an electrically controlled source of fluid fuel supply for the burner, a fuel supply relay having contacts controlling said fuel said auxiliary winding, 2. second relay having two sets of contacts, one set of said'contacts controlling the energization of said fuel supply relay, and the other of said contacts controlling the energization of said electrically controlled air supply, the winding of said second relay being in said primary circuit, said transformer having magnetic means for short circuiting flux under predetermined conditions whereby the safety system is adapted to be shut down without supply of fuel unless the spark adapted to be supplied by said secondary winding is of suitable characteristics for ignition under air blast conditions.

2. In a safety fuel supply system for combustion devices, the combination of a source of alternating current with a step-down transformer, a room thermostat for controlling electric contacts responsive to the demand for heat, a main relay controlled by said room thermostat and having contacts for controlling the energization of an ignition transformer, a thermostatic stack switch having contacts controlling the energization of said main relay, a warp switch having a thermostatic switch arm and an electric heater, contact means and latching means whereby the warp switch will hold the main relay winding on open circuit upon failure of ignition, said stack switch superseding said warp switch upon heating of the stack, an ignition transformer having a primary, secondary, and auxiliary windings, said primary being controlled by said main relay, and having a magnetic core with a plurality of legs, said primary being located on said core, and said core also supporting said secondary, and said auxiliary winding, an electrically actuated source of air supply for the burner, an electrically controlled source of fluid fuel supply for the burner, a fuel supply relay having contacts controlling said fuel supply, said fuel supply relay being in circuit with said auxiliary winding, a second relay having two sets of contacts, one set of said contacts controlling the energization of said fuel supply relay, and the other of said contacts controlling the energization of said electrically controlled air supply, the winding of said second relay being in said primary circuit, said transformer having magnetic means for short circuiting flux under predetermined conditions whereby the safety system is adapted to be shut down without supply of fuel unless the spark adapted to be supplied by said secondary winding is of suitable characteristics for ignition under air blast conditions, said circuit being arranged for continuous ignition at a spark gap controlled by said secondary while the burner is operating.

3. In a safety fuel supply system for combustion devices, the combination of a source of alternating current with a step-down transformer, a room thermostat for controlling electric contacts responsive to the demand for heat, a main relay controlled by said room thermostat and having contacts for controlling the energization of an ignition transformer, a thermostatic stack switch having contacts controlling the energization of said main relay, a warp switch having a thermostatic switch arm and an electric heater, contact means and latching means whereby the warp switch will hold the main relay winding on open circuit upon failure of ignition, said stack switch superseding said warp switch upon heating of the stack, an ignition transformer having a primary, secondary, and auxiliary windings, said primary being controlled by said main relay, and having a magnetic core with a plurality of legs, said primary being located on said core, and said core also supporting said secondary, and said auxiliary winding, an electrically actuated source of air supply for the burner, an electrically controlled source of fluid fuel supply for the burner, a fuel supply relay having contacts controlling said fuel supply, said fuel supply relay being in circuit with said auxiliary winding, a second relay having two sets of contacts, one set of said contacts controlling the energization of said fuel supply relay, and the other of said contacts controlling the energization of said electrically controlled air supply, the winding of said second relay being in said primary circuit, said transformer having magnetic means for short circuiting flux under predetermined conditions whereby the safety system is adapted to be shut down without supply of fuel unless the spark adapted to be supplied by said secondary winding is of suitable characteristics for ignition under air blast conditions, said system being arranged for intermittent ignition of the spark gap in the circuit of said secondary winding, said stack switch also including contact means for controlling the energization of said transformer and for deenergizing said transformer after a predetermined period of time.

4. In a fuel control system for combustion devices, the combination of electrically controlled air feed means for supplying a blast of combustion air with electrically controlled fuel feed means, electric ignition means including a pair of spaced electrodes arranged for a spark gap in the path of travel of the combustion air, an ign i t i on tran s former for selectively controlling the air feed means'aiidthe 4 W "M s, said transformer having'a'priifi Winding, a secondary winding, and an auxiliary coil, said secondary winding being connected in circuit with said spaced elec trodes of the spark gap, and said auxiliary winding controlling the energization of said fuel feed means, and means congglledbyjaid.tlfan fi ifmfi for enr ii fisififie-anersisiaa sa i i: eed rfi'a'fi prior to the energization of said uel feed means, said ignition transformer being constructgd and'iarrariged to prevent the energizat1'ori ofsaid fuel feedineans i nless the spark suppfi flfi JQRJ IEQP. iSHO USuitabIe characteristics fc rignition under air blast conditions.

5 In a fuel dntreisystein for combustion devices, the combination of electrically controlled air feed means for supplying a blast of combustion air with electrically controlled fuel feed means, electric ignition means including a pair of spaced electrodes arranged for a spark gap in the path of travel of the combustion air, an ignition transformer for Selectively controlling the air feed means and the fuel feed means, said transformer having a primary winding, a secondary winding, and an auxiliary coil, said secondary winding being connected in circuit with said spaced electrodes of the spark gap, and said auxiliary winding controlling the energization of said fuel feed means, and means controlled by said transformer for energizing or deenergizing said air feed means prior to the energization of said fuel feed means, said ignition transformer being constructed and arranged to prevent the energization of said fuel feed means unless the spark supplied at said air gap is of suitable characteristics for ignition under air blast conditions, said ignition transformer having a closed core provided with means for short circuiting flux under predetermined conditions and proportioned to maintain substantially uniform spark conditions at the gap over a wide range of voltages applied at the primary of said transformer.

6. In a fuel control system for combustion devices, the combination of electrically controlled air feed means for supplying a blast of combustion air with electrically controlled fuel feed means, electric ignition means including a pair of spaced electrodes arranged for a spark gap in the path of travel of the combustion air, an ignition transformer for selectively controlling the air feed means and the fuel feed means, said transformer having a primary Winding, a secondary winding, and an auxiliary coil, said secondary winding being connected in circuit with said spaced electrodes of the spark gap, and said auxiliary winding controlling the energization of said fuel feed means, and means controlled by said transformer for energizing or deenergizing said air feed means prior to the energization of said fuel feed means, said ignition transformer being constructed and arranged to prevent the energization of said fuel feed means unless the spark supplied at said air gap is of suitable characteristics for ignition under air blast conditions, said fuel feed means comprising an electrically driven pump for supplying liquid fuel under pressure.

7. In a fuel control system for combustion devices, the combination of electrically controlled air feed means for supplying a blast of combustion air with electrically controlled fuel feed means, electric ignition means including a pair of spaced electrodes arranged for a spark gap in the path of travel of the combustion air, an igni tion transformer for selectively controlling the air feed means and the fuel feed means, said transformer having a primary winding, a secondary winding, and an auxiliary coil, said secondary winding being connected in circuit with said spaced electrodes of the spark gap, and said auxiliary winding controlling the energization of said fuel feed means, and means controlled by said transformer for energizing or deenergizing said air feed means prior to the energization of said fuel feed means, said ignition transformer being constructed and arranged to prevent the energization of said fuel feed means unless the spark supplied at said air gap is of suitable characteristics for ignition under air blast conditions, said fuel feed means comprising an electrically actuated valve for controlling the flow of fuel to a burner.

8. In a fuel control system for combustion devices, the combination of electrically controlled air feed means for supplying a blast of combustion air with electrically controlled fuel feed means, electric ignition means including a pair of spaced electrodes arranged for a spark gap in the path of travel of the combustion air, an ignition transformer for selectively controlling the air feed means and the fuel feed means, said transformer having a primary winding, a secondary winding, and an auxiliary coil, said secondary winding being connected in circuit with said spaced elect-rodes of the spark gap, and said auxiliary winding controlling the energization of said fuel feed means, and means controlled by said transformer for energizing or deenergizing said air feed means prior to the energization of said fuel feed means, said ignition transformer being constructed and arranged to prevent the energization of said fuel feed means unless the spark supplied at said air gap is of suitable characteristics for ignition under air blast conditions, said ignition transformer having a closed core provided with means for.

short circuiting flux under predetermined conditions and proportioned to maintain substantially uniform spark conditions at the gap over a wide range of voltages applied at the primary of said transformer, said means for short circuiting flux being disposed between the primary winding and the other two windings, and said windings being located upon the same portion of said core.

9. In a fuel control system for combustion devices, the combination of electrically controlled air feed means for supplying a blast of combustion air with electrically controlled fuel feed means, electric ignition means including a pair of spaced electrodes arranged for a spark gap in the path of travel of the combustion air, an ignition transformer for selectively controlling the air feed means and the fuel feed means, said transformer having a primary winding, a secondary winding, and an auxiliary coil, said secondary winding being connected in circuit with said spaced electrodes of the spark gap, and said auxiliary winding controlling the energization of said fuel feed means, and means controlled by said transformer for energizing or deenergizing said air feed means prior to the energization of said fuel feed means, said ignition transformer being constructed and arranged to prevent the energization of said fuel feed means unless the spark supplied at said air gap is of suitable characteristics for ignition under air blast conditions, said ignition transformer having a closed core provided with means for short circuiting flux under predetermined conditions and proportioned to maintain substantially uniform spark conditions at the gap over a wide range of voltages applied at the primary of said transformer, said transformer having windings disposed about said flux short circuiting means, and said latter windings being connected to a relay controlling both the fuel and the air feed.

10. In a fuel control system for combustion devices, the combination of electrically controlled air feed means for supplying a blast of combus tion air with electrically controlled fuel feed means, electric ignition means including a pair of spaced electrodes arranged for a spark gap in the path of travel of the combustion air, an ignition transformer for selectively controlling the air feed means and the fuel feed means, said transformer having a primary winding, a secondary winding, and an auxiliary coil, said secondary winding being connected in circuit with said spaced electrodes of the spark gap, and said auxiliary winding controlling the energization of said fuel feed means, and means controlled by said transformer for energizing or deenergizing said air feed means prior to the energization of said fuel feed means, said ignition transformer being constructed and arranged to prevent the energization of said fuel feed means unless the spark supplied at said air gap is of suitable characteristics for ignition under air blast conditions, said ignition transformer having a closed core provided with means for short circuiting flux under predetermined conditions and proportioned to maintain substantially uniform spark conditions at the gap over a wide range of voltages applied at the primary of said transformer, and relay means connected to the primary winding of said transformer for controlling the energization of said air feed means and said fuel feed means.

11. In a fuel control system for combustion devices, the combination of electrically controlled air feed means for supplying a blast of combustion air with electrically controlled fuel feed means, electric ignition means including a pair of spaced electrodes arranged for a spark gap in the path of travel of the combustion air, an ignition transformer for selectively controlling the air feed means and the fuel feed means, said transformer having a primary winding, a secondary winding, and an auxiliary coil, said secondary winding being connected in circuit with said spaced electrodes of the spark gap, and said auxiliary winding controlling the energization of said fuel feed means, and means controlled by said transformer for energizing or deenergizing said air feed means prior to the energization of said fuel feed means, said ignition transformer being constructed and arranged to prevent the energization of said fuel feed means unless the spark supplied at said air gap is of suitable characteristics for ignition under air blast conditions, said ignition transformer having a closed core provided with means for short circuiting fiux under predetermined conditions and proportioned to maintain substantially uniform spark conditions at the gap over a wide range of voltages applied at the primary of said transformer, relay means connected to the primary winding of said transformer for controlling the energization of said air feed means and said fuel feed means, and a second relay means controlled by the first-mentioned relay means and connected to said auxiliary winding for effecting the control of said fuel feed means.

12. In a fuel control system for combustion devices, the combination of electrically controlled air feed means for supplying a blast of combustion air with electrically controlled fuel feed means, electric ignition means including a pair of spaced electrodes arranged for a spark gap in the path of travel of the combustion air, an ignition transformer for selectively controlling the air feed means and the fuel feed means, said transformer having a primary winding, a secondary winding, and an auxiliary coil, said secondary winding being connected in circuit with said spaced electrodes of the spark gap. and said auxiliary winding controlling the energization of said fuel feed means, and means controlled by said transformer for energizing or deenergizing said air feed means prior to the energization of said fuel feed means, said ignition transformer being constructed and arranged to prevent the energization of said fuel feed means unless the spark supplied at said air gap is of suitable characteristics for ignition under air blast conditions, said ignition transformer having a closed core provided with means for short circuiting fiux under predetermined conditions and proportioned to maintain substantially uniform spark conditions at the gap over a wide range of voltages applied at the primary of said transformer, said system being arranged for continuous ignition at the spark gap controlled by said secondary while the burner is operating.

13, In a fuel control system for combustion devices, the combination of electrically controlled air feed means for supplying a blast of combustion air with electrically controlled fuel feed means, electric ignition means including a pair of spaced electrodes arranged for a spark gap in the path of travel of the combustion air, an ignition transformer for selectively controlling the air feed means and the fuel feed means, said transformer having a primary winding, a secondary winding, and an auxiliary coil, said secondary winding being connected in circuit with said spaced electrodes of the spark gap, and said auxiliary winding controlling the energizaotlili illi iiUiiiil tion of said fuel feed means, and means controlled by said transformer for energizing or deenergizing said air feed means prior to the energization of said fuel feed means, said ignition transformer being constructed and arranged to prevent the energization of said fuel feed means unless the spark supplied at said air gap is of suitable characteristics for ignition under air blast conditions, said ignition transformer having a closed core provided with means for short circuiting flux under predetermined conditions and proportioned to maintain substantially uniform spark conditions at the gap over a wide range of voltages applied at the primary of said transformer, said system being arranged for intermittent ignition of the spark gap in the circuit of said secondary Winding while the burner is operating.

14. In a safety fuel supply system for combustion devices, the combination of an ignition transformer having a primary, secondary, and auxiliary windings, said primary being controlled by said main relay, and having a magnetic core with a plurality of legs, said primary being located on said core, and said core also supporting said secondary, and said auxiliary winding, an electrically actuated source of air supply for the burner, an electrically controlled source of fluid fuel supply for the burner, a fuel supply relay having contacts controlling said fuel supply, said fuel supply relay being in circuit with said auxiliary winding, a second relay having two sets of contacts, one set of said contacts controlling the energization of said fuel supply relay, and the other of said contacts controlling the energization of said electrically controlled air supply, the winding of said second relay being in said primary circuit, said transformer having magnetic means for short circuiting flux under predetermined conditions whereby the safety system is adapted to be shut down without supply of fuel unless the spark adapted to be supplied by said secondary winding is of suitable characteristics for ignition under air blast conditions.

15. In a fuel control system for combustion devices, the combination of electrically controlled air feed means for supplying a blast of combustion air with electrically controlled fuel feed means, a relay for controlling the energization of said fuel feed means, and an ignition transformer, said transformer having a primary winding, a secondary winding connected to ignition electrodes to effect ignition under air blast conditions, and an auxiliary winding, said relay having its contacts connected in series with said auxiliary winding for controlling the energization of the fuel feed means, said transformer having a core, and said windings and core and relay being so proportioned and arranged in respect to each other that a. short circuit in said secondary winding will limit the amount of cur rent flowing in said auxiliary winding in such manner that said relay will not be actuated, thus preventing the actuation of said fuel feed means.

16. In a fuel control system for combustion devices, the combination of electrically controlled air feed means for supplying a blast of combustion air With electrically controlled fuel feed means, a relay for controlling the energization of said fuel feed means, and an ignition transformer, said transformer having a primary winding, a secondary winding connected to ignition electrodes to effect ignition under air blast conditions, and an auxiliary winding, said relay having its contacts connected in series with said auxiliary winding for controlling the energization of the fuel feed means, said transformer having a core, and said windings and core and relay being so proportionedand arranged in respect to each other that a short circuit in said secondary winding will limit the amount of current flowing in said auxiliary winding in such manner that said relay will not be actuated, thus preventing the actuation of said fuel feed means, said system also including another relay having its winding in series with the primary of said transformer, said second mentioned relay having its contacts controlling the circuit of the first mentioned relay, whereby an open circuit in the secondary of the transformer will so limit the current in the primary winding that the second mentioned relay will not be actuated to close the circuit of the first-mentioned relay, thereby preventing the supply of fuel ung gf giphengg msrssamentprmr circuit.

VOYLE D. OTT. 

